Continuous dielectric heating means



May 25, 1954 P. D. NEWHOUSE CONTINUOUS DIELECTRIC HEATING MEANS FiledApril 1, 1949 2 Sheets-Sheet l n Fig.l.

WITNESSES: INVENTOR PAUL .D. NEWHOUSE.

ATTORNEY y 25, 1954 Y P. D. NEWHOUSE ,6

- CONTINUOUS DIELECTRIC HEATING MEANS Filed Apx il l, 1949 2Sheets-Sheet 2 WITNESSES: INVENTOR PAUL 0-. NEWHOUSE.

BY I ATTORNEY Patented May 25, 1954 CONTINUOUS DIELECTRIC HEATING MEANSPaul D. Newhouse, Salix, Iowa, assignor to Westinghouse ElectricCorporation, East Pittsburgh, Pa., a corporation of PennsylvaniaApplication April 1, 1949, Serial No. 84,882

(Cl. 2l9-l0.69)

Claims.

My invention relates more directly to dielectric heating of a type whichinvolves one or more roller-type heating-electrodes providing anelectric field through which material or work is continuously passed fordielectric heat treatment;

but it is to be understood that my invention has broader application.

In conventional dielectric heating practice, work is dielectricallyheated while it is between a pair of relatively-insulatedheating-electrodes across which a high-frequency voltage exists. In thecase of elongated work, such as sheet material, the work is usuallyheat-treated while it continually moves between the heating electrodeswhich are frequently tubular members in the form of rollers. Sometimesthe rollers are under pressure. To convey electric power to suchrollers, it has been customary to use insulated or uninsulated slidingor rolling contacts, brushes, or similar expedients which frequentlybecome troublesome-especially at the high frequencies required fordielectric heat treatment.

The primary object of my invention is to provide a dielectric heatingsystem and elements therefor of a type described comprising one or morerollers energized without the use of insulated or uninsulated sliding orrolling contacts, brushes or the like.

A further object of my invention is to provide a dielectric heatingsystem of the aforesaid rollertype in which pressure can be applied tothe roller or rollers While the roller or rollers are energized.

A specific object of my invention is to provide a novel and improvedroller-type heating-electrode to which energy can be supplied by meansof a member out of contact with the roller portion of theheating-electrode.

Further objects, features and innovations of my invention will bediscernible from the following description of several embodimentsthereof. The description is to be taken in conjunction with theaccompanying schematic drawings which are limited to such parts anddetails as are necessary for an understanding of the principlesunderlying my invention. In the drawings:

Figure 1 is a side elevational view of a dielectric heating systemembodying my invention;

Fig. 2 is a vertical sectional view substantially along the line 11-11of Fig. 1, axially through a set of heating-electrodes embodyingfeatures of my invention;

Fig. 3 is a sectional view on the line III-III of Fig. 2;

Fig. 4 is an elevational view of part of a modifled form of aroller-type heating-electrode;

Fig. 5 is a vertical sectional view through a modified form ofheating-electrodes embodying my invention;

Fig. 6 is a vertical sectional view of still another embodiment of myinvention; and

Fig. '7 is a partial sectional view along the lines VII-Jill of Fig. 6.

1 generally illustrates a dielectric system embodying my invention.Elongated work or material 2 moves between as many sets or pairs ofroller-means as a particular application may require. Four such sets ofroller-means 4, 6, 8 and. is are shown in Fig. l. The set of rollermeans4 may pull the material through the work line in the direction of thearrow shown in Fig. 1, and as many other sets of roller-means may beused as drive or feed rollers as desired. Sometimes drag units are alsodesired for controlling the tension in the material, and the set ofrollermeans It may be of this type. The intermediate sets ofroller-means 6 and 8 are constructed in accordance with my invention soas to provide an electric field for heating the work 2 as it passesbetween these sets of roller-means. Since each set may be alike, it isapparent that my invention should be understood from a description of asingle set.

Accordingly, the set 6 of roller-means comprises a pair ofheating-electrodes, each being indicated in its entirety by thereference numeral 12 or It. The lower heating-electrode [-2 comprises anouter hollow, round tubular member or roller 16 preferably of copper.Spaced bases 18 and 2B of insulating material are inside the tubularmember. In this particular instance, the bases are in the form of disksand are located at the ends of the tubular member iii. Base-ends l8 and2t have central holes 22 and i l, respectively, so as to loosely receivea rod or shaft 26 preferably of copper. A shaft 26 rotatably carries thetubular member I6 through bearings 38 secured to the base-ends l8 and20. The shaft 26 is relatively stationary with respect to the tubularmember :6 and is adequately insulated therefrom by the insulating basesI8 and '28. Secured to the shaft 26 in good electrical contact therewithis a hollow metal inner cylinder 36 comprising a tube 32 closed by ends33. This cylinder is preferably of copper and the tube 32 is inside ofand concentric with the tubular member or roller IE, but spaced at allpoints therefrom so as to provide a capacitive coupling thereto.

The heating-electrode I4 is constructed in the same manner as theheating-electrode l2. It comprises an outer hollow, round tubular memheror roller 34, base-ends 36 and 38 having central holes 40 and 42,bearings M, a stationary shaft d6 passing through the bearings, and aconducting cylindrical structure inside the tubular member 34. Thisconducting structure comprises a tube 48 concentric with the tubularmember 34 and ends 49 secured to the shaft 46 by any suitable meanswhich includes a conductive connection.

The ends of the shafts 26 and 46 are carried in parallel relation by anysuitable supporting means. As shown in Fig. 2, such supporting meanscomprises fixed supports 50 of insulating material for the shaft 26 andinsulating supports 52 for the shaft 46. The supports 52 carry the shaft45 in any suitable manner that permits the shaft 48 to be pressed orforced toward the other shaft 26. To this end, the supports 50 and 52 oneach side of the heating-electrodes I2 and I4 are mechanicallyinterconnected through any suitable pressure-exerting means, such as forexample, a pneumatically-operated interconnection 54 between thesupports. The pneumatic connection comprises a piston 56. A spring 58acts on one side of the piston and gas pressure applied through pipes 60acts on the other side of the piston 56.

An end of each of the shafts 26 and M of the heating-electrodes l2 and14 extends beyond a pair of the supports 50 and 52. To these protrudingends, high-frequency power may be connected as shown in Fig. 2. Themeans for supplying high-frequency energy to the shafts consists of atransmission line 62 having conductors 64 and 66 which can be suppliedwith high-frequency energy by any suitable tube-oscillator generator(not shown) Assuming that there is high-frequency energy on thetransmission line 62, the power flows from the shafts 2S and 46 to thetwo metallic tubes 32 and 48. A high-frequency voltage will exist acrossthem. Because of the capacitive coupling between the roller 34 and tube48 and between the roller l6 and tube 32, a somewhat lower highfrequencyvoltage will also exist between the facing surface-portions of therollers; by facing surface-portions, meaning those parts of the rollersthat face each other and provide a concentrated electric field in thespace between the rollers that heats the work 2 moving between therollers. As the Work 2 moves, the rollers I6 and 3&1 roll around theshafts 25 and 46, respectively, so that their facing surface-portionsare constantly changing.

The shafts 26 and 4B and the tubes 32 and 48 can be said to bestationary with respect to the rotating tubular members or rollers 16and 34; but it is to be understood that I do not use the word stationaryas necessarily synonymous with fixed because the pressure-exertingmeans, (comprising the mechanical interconnection 54 between the shafts26 and 46) if used, provides a limited amount of relative movementbetween the shafts. Moreover, they can be adjustably supported, ifdesired.

Ordinarily, the space inside a roller, such as the space between thehollow cylindrical roller I6 and the cylindrical tube 32 is gaseous andcan be air so that the nested cylinders need not be air-tight. However,the nested cylinders can be made liquid-tight or gas-tight so as to beable to hold a dielectric liquid or a gas other than air.

In the embodiment shown in Figs. 2 and 3, the hollow tubular members orrollers l6 and 34 of the heating-electrodes l2 and M are of the idlingtype, being rotated by the moving material. However, they can be drivingrollers if desired and can be driven in any suitable manner. Fig. 4shows a simple expedient that may be used to convert one or both of theidling rollers to driving rollers, but other expedients can obviously beused. In Fig. 4, an end-base 20 for the roller It is provided with adrum '10 around which may be wrapped an insulating driving belt 12. Thedrum is insulated from the tubular member or roller it by the insulatingend-base 20.

Instead of transferring electrical energy to the rollers of theheating-electrodes from inside the rollers, the energy can betransferred to them from the outside. Consequently, he rollers can bemade solid, if desired, and capable of exerting a higher pressure on thematerial or work being heat treated. An embodiment of this kind is shownin Fig. 5 where heating-electrodes M and iii comprise insulatedly androtatably-supported, solid metal rollers 18 and 80, respectively. Curvedparti-cylindrical conducting members 82 and 84 are concentrically aroundportions of the outside of the rollers 18 and 80, respectively, beingspaced therefrom for capacitive coupling. By attaching conductors 86 and88 of a highfrequency transmission line to these stationary curvedmembers 82 and 84, hi h-frequency energy is capacitively transferred tothe rollers 13 and 81!; and a highly concentrated electric field isprovide-d between the facing surface-portions of the rollers betweenwhich the work moves. Each member 82 or 84 terminates at any desireddistance from the work, and can be made of more than one segment.

In applications where rollers of large diameters are required, it mightbe objectionable to have a large part of the heating-electrodeselectrically energized for many different reasons, such as for example,excessive capacitance or excessive electrical radiation, etc. Forapplications of this kind, the embodiment shown in Figs. 6 and '7 isrecommended. In this embodiment, the heating-electrodes comprise hollowouter tubular members or rollers 90 and 52 that are insulatedlyrotatably supported while pressed together in any suitable manner, suchas for example, by the construction shown in Figs. 2 and 3. Each rolleris segmented, being made up of similar segments or strips of metalseparated by narrow segments or strips of insulation. More specifically,each roller comprises a plurality of circumferentiallyspacedaxially-extending insulating portions 96. Alternating with theseinsulating portions are similarly arranged conducting sections 98.Accordingly, each conducting section 58 is insulated from all the otherconducting sections of the tubular members 90 and 92 by the insulatingportions 96. In the preferred embodiment, the axial sides of thesegments are parallel to the axis of the roller.

Each heating-electrode also comprises a stationary curved plate Hillclose to the portion of a roller that faces the work to be heat treatedand the other roller. This plate it!) is a longitudinal part of acylinder and has an axis which is preferably concentric with, orparallel to, a conducting section of the roller. Circumferentially,however, the plate is slightly wider than the circumferential width of asingle conducting section 93, but it can be of more or less width.

ihe stationary plates I00 of the heating-electrodes 8t and 92 areconnected in any suitable manner to conductors I02 and I04 of ahighfrequency transmission line. These connections may include thestationary shafts around which the rollers 90 and 92 rotate, in a mannersimilar to the embodiment previously described in connection with Figs.2 and 3.

It is desirable to so angularly displace the rollers tit and 92 of theheating electrodes 86 and 38 that their insulating segments 96 do notcome exactly opposite to each other as they rotate past the space inwhich the work moves. In this way, a more uniform electric field betweenthe rollers is obtained because no two in sulating segments 96 ondifferent rollers ever come exactly opposite to each other. Fig.6indic'ates a proper arrangement, and to maintain this arrangement it isdesirable to synchronize the rotation of the rollers.

In the embodiment described in Figs. 6 and '7, it is evident that onlythe facing conducting segments or sections 98 of the rollerheatingelectrodes 90 and 92 will be strongly electrically energized,since significant capacitive coupling to the other sections 98 islimited by the circumferential extent of the plates I00. Ifelectrification of additional or a greater number of conducting sections98 is desired, as many conducting jumpers as desired may be usedelectrically interconnecting them.

While I have described my invention in many forms, which I now prefer,it is obvious that the principles of my invention may be widely appliedin different forms and modifications. For example, another form isdisclosed and claimed broadly in my application Serial No. 84,881, filedconcurrently herewith, now Patent No. 2,644,073.

I claim as my invention:

1. Dielectric heating means of a type described comprising, incombination, heating-electrodes comprising a pair of rotatable rollers,supporting means insulatedly supporting each of said rollers from groundfor the passage of work therebetween, power-applying means for applyinga high-frequency voltage across said heating-electrodes to provide anelectric field therebetween for heating said work, each of said rollershaving an outer metallic surface-portion at which said field isconcentrated, said power-applying means comprising a metallic member foreach of said rollers, each of said metallic members being elongated in adirection axially of said rollers and positioned within its respectiveroller, and supporting means supporting said metallic members insulatingspaced from said metallic surface-portions in stationary energy-feedingcapacitive coupling relation thereto.

2. Dielectric heating means of a type described,

comprising, in combination, a pair of relativelyinsulated spacedheating-electrodes, a first of said heating-electrodes comprising aroller in the form of a hollow tubular member having a metallicsurface-portion adapted to face the second of said heating-electrodes,supporting means insulatingly and rotatably supporting said roller, saidsupporting means comprising bases for said tubular member, bearing meansassociated with said bases and a stationary shaft carried in saidbearing means, a metallic member inside said roller and secured to saidshaft so that said metallic member is stationary with respect to saidroller, said metallic member being elongated axially of the roller andspaced from but in energy-feeding capacitive coupling relation to saidsurface-portion when the latter faces said second heating-electrode, andmeans comprising a conductor associated with said shaft for connecting asource of high-frequency energy across said metallic member and saidsecond heating-electrode.

3-. An invention including that of claim 2 but characterized further bymetallic member being a tube.

4. An invention including that of claim 3 but further characterized bysaid roller of said first heating-electrode comprising a plurality ofinsulated sections.

5. Dielectric heating means of a type described, comprising, incombination, a pair of relativelyinsulated spaced heating-electrodes, afirst of said heating-electrodes comprising a roller in the form of ahollow tubular member having a metallic surface portion adapted to facethe sec- 0nd of said heating-electrodes, said first heatingelectro'decomprising a shaft insulatingly and rotatably carrying said roller, anda stationary metal member inside ofand fixedly spaced from the insidesurface of said roller and capacitively coupled to said surface-portion,and means for connecting a source of high-frequency across said metalmember and said second heatingelectrode.

6. Dielectric heating means of a type described, comprising, incombination, a pair of relativelyinsulated rollers, each roller being inthe form of a hollow tubular member having a metallic surface-portionadapted to face the other of said rollers, a stationary meansinsulatingly and rotatably carrying said rollers, a stationary metalmember inside of and fixedly spaced from the inside surface of each ofsaid rollers and capacitively coupled to the surface-portion thereof,and means for connecting a source of high-frequency across saidstationary metal members.

'7. A dielectric heating-electrode of a type described comprising ahollow-roller having a conducting portion, a shaft which is relativelystationary with respect to said roller, structural means between saidshaft and roller constructed and arranged so that said shaft isinsulated from but rotatably carries said roller, a curved metallicmember inside said roller adapted to be capacitively coupled to saidconducting portion, said metallic member being relatively stationarywith respect to said roller, and a high-frequency connection to themetallic member.

8. A dielectric heating-electrode of a type described, comprising, ahollow cylindrical member having an outer surface member and a pair ofspaced insulating bases, a shaft extending through one of said bases,said shaft being stationary and rotatably carrying said cylindricalmember, an inner metallic curved member inside said cylindrical member,said curved member being attached to said shaft, and an energizingconductor secured to said shaft.

9. Dielectric heating means of a type described comprising, incombination, a pair of heatingelectrodes, each of saidheating-electrodes comprising a rotatable tubular member, the tubularmembers being spaced to provide a space therebetween in which work canbe dielectrically heat treated, at least one of said tubular memberscomprising a plurality of successive insulating and conducting segments,and means for supplying high-frequency energy to saidheating-electrodes, with the last said means comprising a curved memberinside said one tubular member, said curved member being of limitedcircumferential length and spaced from but facing a conduction segmentwhen the latter segment is facing said space.

10. Dielectric heating means of a type described comprising, incombination, a pair of heatingelectrodes, each of saidheating-electrodes comprising a rotatable tubular member, the tubularmembers being spaced to provide a space therebetween in which work canbe dielectrically heat treated, each of said tubular members comprisinga plurality of circumferentially-spaced insulating portions extendinglengthwise thereof, and conduction sections between the insulatingportions, means for rotating said tubular members, and means forapplying a high-frequency voltage to the conduction sections at saidspace without applying such voltage to conduction sections away fromsaid space.

11. An invention including that of claim 10 but further characterized bysaid tubular members being arranged so that their insulation portions donot lie in the same angular relation, opposite each other, when the lastsaid insulating portions are in said space.

12. Dielectric heating means comprising a tu- :bular member comprising aplurality of circumferentially-spaced insulating portions extendinglengthwise thereof and conduction sections between said insulatingportions, and means for electrically energizing a limited number ofsections, the said number being less than the total number of saidsections.

13. Dielectric heating means comprising a tubular member comprising aplurality of successive insulating and conducting segments, a stationaryshaft, means for insulatedly and rotatably mounting said tubular memberon said shaft, and means positioned within but spaced from said tubularmember for electrically energizing a number of said conducting segmentsduring rotation of said tubular member.

14. Dielectric heating means of a type described comprising aheating-electrode comprising a tubular member, said tubular membercomprising a plurality of circumferentially spaced insulating portionsand conducting sections between said insulating portions, and a couplingmember positioned within and capacitively coupled to said tubular memberfor supplying highfrequency energy to a predetermined number of saidconduction sections.

15. A dielectric heating-electrode comprising, a hollow rotatabletubular member comprising a plurality of circumferentially-spacedinsulating portions and a plurality of conducting sections between theinsulating portions, and a stationary metallic conducting member insidesaid tubular member, spaced therefrom, said conducting member spanningless than all of said conduction sections.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 2,231,457 Stephen Feb. 11, 1941 2,248,840 Wilkofi July 8, 19412,324,068 Crandell July 13, 1943 2,459,622 Cohoe et a1 Jan. 18, 1949-2,459,623 Cohoe et al Jan. 18, 1949 2,476,283 Castellan July 19, 19492,525,356 Hoyler Oct. 10, 1950 2,551,756 Mittelmann May 8, 19512,589,777 Collins Mar. 18, 1952 FOREIGN PATENTS Number Country Date573,021 Great Britain Nov. 2, 1945 609,192 Great Britain Sept. 27, 1948915,377 France Nov. 5, 1946

